Fix arg name format

Author: Matthew-Whitlock

.github/docker-compose.yml

@@ -5,14 +5,14 @@ services:
       dockerfile_inline: |
         FROM spack/ubuntu-jammy:latest
         VOLUME /configs
-        ARG ompi_version
-        ENV ompi_version=$$ompi_version
+        ARG OMPI_VERSION
+        ENV OMPI_VERSION=$${OMPI_VERSION}
         CMD cp /configs/spack.yaml . && \
-            spack -e . add openmpi@$${ompi_version} && \
+            spack -e . add openmpi@$${OMPI_VERSION} && \
             spack -e . containerize >/configs/spack.Dockerfile && \
             sed -i -e 's/spack install/spack external find --all --not-buildable \&\& spack install/;' /configs/spack.Dockerfile
       args:
-        ompi_version: main
+        OMPI_VERSION: main
       no_cache: true
     pull_policy: build
     volumes: